Granular fertilizer for plants containing a type of mycorrhizal fungus

ABSTRACT

The invention relates to a granular fertilizer for plants, the grains of said fertilizer containing spores and/or mycellium of at least one type of mycorrhizal fungus in sufficient amounts to ensure symbiosis.

BACKGROUND OF THE INVENTION

The invention relates to a granular fertilizer for plants.

This type of fertilizer forms for example the subject of DE 44 24 574A1. This previously known fertilizer uses malt germs which are generatedin the process of malting ale cereals and are removed from the maltgrain after drying has been accomplished. It is granular, which isappropriate for spreading. Typically, the grains fit through sieveopenings with square or round holes, the side length or the diameter ofwhich ranges from 3 to 5 mm. Larger- or smaller-sized sieve widths arenot excluded, though.

In principle, the fertilizer of the type mentioned herein above hasproved very efficient. As compared to other fertilizers, a considerablyhigher mass of as roots has been observed for example.

In principle, fertilizers denote all kinds of plant nutrients. Usually,a fertilizer contains nitrogen, phosphorus and potassium. But thesecomponents need not necessarily be contained and more particularly donot have to be contained in the share prescribed by the nationalRegulations for the minimum requirements made upon a fertilizer.

SUMMARY OF THE INVENTION

It is the object of the present invention to develop a fertilizer likefor example the previously known fertilizer described in the abovementioned published application in such a way that additives are addedthat do not nourish the plant but that associate with the roots of ahigher plant while mutually exchanging substances.

This object is achieved by a granular fertilizer for plants thatcontains in its grains spores and/or the mycelium of at least one typeof a mycorrhizal fungus.

DETAILED DESCRIPTION

Mycorrhiza designates the association of a fungus and the roots of ahigher plant, a symbiotic relationship being thereby formed. Such amycorrhizal symbiosis between the roots of higher plants and the hyphaeof the fungus not only serves to improve the absorption of water andmineral nutrients, the fungus is moreover capable of protecting theplant against toxic organisms by producing antibiotic substances.

There are two types of micorrhizae:

The endotrophic mycorrhizae on one hand, called endomycorrhizae inshort. In this. type of mycorrhiza, the hyphae of the fungus grow intothe cells of the plant's roots. This type of mycorrhiza is particularlysuited for agricultural useful plants.

On the other hand, the ectotrophic mycorrhiza, called ectomycorrhizae inshort. It predominates on trees of the temperate zones. In this type ofmycorrhiza, the fungus grows into the roots of the host and the hyphaepenetrate between the outer cells of the bark. They thereby form atypical, labyrinth-like structure. The fungus forms a mantle of hyphaeon the surface of the roots, said mantle having a structure that istypical of the ectomycorrhizae. The mantle of hyphae mechanicallyprotects the tips of the roots, encapsulates the root that is no longerin contact with the soil, protecting it thus against an invasion bypathogens. It furthermore serves to store calcium, potassium,carbohydrates, phosphates and nitrogen compounds.

Through the mycelium of the fungus, mycorrhizal roots can gain access toa larger volume of soil than uninfected ones. The surface that is activein taking up nutrients is strongly enlarged. Thanks to the fungus, theplant can make better use of both organic and inorganic sources ofnitrogen, even when the potential of soil water is reduced. Thisreservoir of nutrients is then available for both the fungus and theplant.

It has not yet become known to directly combine or mix fertilizers withspores and/or the mycelium of micorrhizae. What is known is to growunder sterile conditions mycelia of the type of fungus of concern as avegetative inoculum on various porous materials, for example on swellingclay. When introducing the vegetative inoculum, it is to be made certainthat the substance used for inoculation survives until the plants hasformed roots. It is difficult to preserve the sterility of thesubstratum until the roots have formed, and in open air it is notpossible. Using sugar as an energy source for the fungus in theunsterile substratum until the mycorrhiza has formed is onlyrestrictedly suited since antagonists that have been born in the soilexploit the energy resources and endanger the survival of the inoculumuntil the roots have formed.

It also has been known to directly admix to the substrata spores in theform of powder or pellets or to apply them as a suspension by sprayingsaid suspension onto a surface of the substratum. This method cannot beused for most of the types of fungus suited for entering intomycorrhizal relationships since they do not produce enough spores.

Hitherto, the mycorrhiza inoculum was introduced into the substratum atdifferential times:

On one hand, the admixture to the substratum is carried out at the timeof sowing, which has the advantage that it does not require anadditional working cycle. The fungus and the plant have the advantage ofthe symbiotic partnership from the very beginning. This is particularlysuited for the method using the spores.

On the other hand, admixing is performed later, e.g. by inoculatingvegetative mycelium. The already mentioned disadvantages arise thereby.It has been known to introduce the inoculum into the substratum duringtransplantation or after the roots have developed. This however requiresan additional working cycle, in which the plants are moreover disturbedin their growth.

The hitherto available technologies are not practicable enough.

The fertilizer according to the invention contains spores of amycorrhizal fungus and/or vegetative mycelium. The fungi are therebyendomycorrhizae or ectomycorrhizae. Examples of ectomycorrhizae arepisolitus tinctorius (arhizus), sclerotinia ranzium, paxfillusinvolutus, lactarius ssp., tuber, boletus edulis, xerocomus badius,hebeloma ssp., laccarina laccarata, laccarina lametistina, soilus ssp.Examples of endomycorrhizae are glomus ssp., rhizoctonia, endogane,acaulospora, gigaspora, scierocystis.

The advantages of the method according to the invention lie in thefollowing:

The fertilizer according to the invention is readily usable in thesectors of horticulture, tree-nurseries, agriculture and hobby.

The actual fertilizer and the mycorrhizal fungus are applied together inone single working cycle.

In the difficult starting phase until the plant has developed its roots,the fungus is capable of growing on account of the nutrients alreadycontained in the fertilizer.

The substratum is invaded by the fungus already before the roots havedeveloped, a mycorrhizal relationship being established from the verybeginning.

Altogether, these advantages make it possible to successfully use thismethod in open air in unsterile substrata.

In a particularly preferred development, the fertilizer according to theinvention is provided with carbohydrates, preferably in 3, preferably inat least 10 weight per cent. The carbohydrates are more specificallypresent in the form of starch and/or sugar. The sugar of particularpreference is maltose, as it is yielded by the malt germs for example.The other starch sources suited for use are more specifically cerealsand potatoes, e.g. amylose and amylosepectin, the sugars, e.g. glucose,fructose, saccharose or raffinose.

In a preferred embodiment, the fertilizer has at least 50 percent inweight malt germs, as they are obtained when ale cereals are malted, andthat are removed from the malt grain after drying. Higher shares of maltgerms, e.g. 60, 70 or 80 percent in weight, up to 100% are advantageous.

It could be proved that with such a type of fertilizer, which containsconsiderable shares of malt germs, the growth of the roots was stronglystimulated. Combined with the inoculation of mycorrhizal fungus, itforms the basis for increased fungus-plant contacts, that is mycorrhizalassociation. The high carbohydrate content, which constitutes animportant source of nutrients for the mycorrhiza, ensures that energy besupplied to the mycorrhiza until symbiosis has been achieved. Thanks tothe granulation, all the nutrients are offered in the zone that mostcontains mycorrhizae, which gives it a competitive advantage overantagonists or parasitic fungi. Moreover, malt germs contain appreciablequantities of yeast fungi. These encourage the formation of mycorrhizalrelationships. The sustained-release property of fertilizers mainlycontaining malt germs is propitious to the development of mycorrhiza andplant since nutrition of the two organisms is guaranteed until thesymbiotic partnership has been established and even after that.

On principle however, any other fertilizer is suited as a carriersubstance. The combination of very efficient types and origins ofmycorrhizal fungi is possible without any problem by admixing them tothe actual fertilizer material.

The fertilizer according to the invention preferably contains at least 5percent by weight, preferably at least 10, and more specifically atleast 20 percent by weight spores of at least one type of mycorrhizalfungus to the ton of final product.

The fertilizer according to the invention makes it possible to combinefavourable properties of plant nutrition and the capacity ofestablishing efficient symbiotic relationships between plant andmicroorganism, which leads to high-yielding plants even under extremeand problematic conditions. This permits to decisively contribute inpreventing erosion and in preserving fertility of soil.

Malt germs in pure form have a nutrient content of typically 5.6%nitrogen, 3.3% phosphate and 3.2% K₂O, all the data being given inpercent by weight. On account of these nutrient contents, malt germs arewell suited to serve as fertilizers. Malt germs consist ofphysiologically young tissue that may readily be mineralised and makecertain of a good fertilizing effect that lasts for approximately onevegetation period. The fertilizer made of malt germs is a fertilizerthat is made on the basis of pure vegetable, organic substances.Inasmuch, malt germs are well suited for being used as a fertilizer.Test results give evidence for the good fertilizing effect of maltgerms.

In its major part, that is in at least 50%, the fertilizer preferablyconsists of malt germs. Further favourable admixtures, which actpositively upon the fertilizing effect, proved to be barley and/or maltdusts as they are obtained for example from malting. These dusts, whichare automatically produced in the process of malting, can be thus usedin a sensible way. Accordingly, in a preferred development thefertilizer contains cereal and/or malt dusts in a ratio of malt germs todusts comprised between from 2/3 to 1/3 and from 3/4 to 1/4.

The cereal and/or malt dusts have a high share of low polymericcarbohydrates and sugar which in turn promote the mineralization ofnutrients because carbohydrates and sugar may serve as nutrients forthose microorganisms that promote the mineralization of nutrients. Themixture of malt germs and dusts typically has a nutrient composition ofapproximately 3.5% nitrogen, 2.2% phosphate and 2.1% K₂O, all the databeing given in percent by weight.

In practical use, a grain size of between 10 by 30 mm and 3 by 5 mmproved particularly favourable. On account of the granulation and of thegrain sizes indicated, the fertilizer according to the invention is easyto apply, it may be spread easily with spreaders or by hand so that italtogether is readily proportionable. The grain sizes of preference aresizes in the lower range, that is near to 3 by 5 mm. Their manipulationis particularly advantageous.

In order to be capable of pelletizing and granulating the mixture ofmalt germs and fungus material, which possibly includes the added barleyand malt dusts, the pressed material has to be moistened. The dry-mattercontent of the malt germs, with the dusts or without them, typicallyamounts to 94%. Moistening of 85to 90% dry matter is suited andnecessary for pelletizing and granulating. Moistening is carried out byadding an aqueous fluid. Said fluid may exclusively consist of water,but it may more specifically and preferably contain additionalfertilizing agents. The flow of water permits to convey nutrients likefor example phosphorus, potassium, magnesium or even micronutrientslike, e.g. copper. On the other side however, the flow of water may bereplaced by liquid fertilizers as they are already available on themarket. By adding nutrients through and in the aqueous fluid, thenutrient ratio of the final fertilizer may be influenced ad lib so thatthe specific demands of a type of plant to be fertilized can be adjustedto. A specific fertilizer for flowering plants, for conifers, forvegetable, strawberries and the like can thus be manufactured.

The invention is explained herein after with the aid of an exemplaryembodiment:

On malting ale cereals, that is in particular barley or wheat destinedfor brewing, radicles are formed, each grain usually forming 3 to 5radicles having a length of about 10 to 14 mm and a diameter ofapproximately between 0.4 and 0.7 mm. On drying, the grain is driedtogether with its radicle. Then, the radicle can be cut off if it hasnot yet been previously removed by mechanical treatment. The malt germsare not to be contained in the finished malt as it is required formaking beer because they affect the brewing process.

Dusts are also produced during the whole process of malting. In thefirst stages of the malting process, the dusts yielded are pure cerealdusts, more particularly barley dusts, in the later stages, malt dustsare produced. To produce the fertilizer according to the invention, themalt germs and the dusts produced per initial quantity of ale cerealused are blended together. In a concrete realization, the ratio ofmixture is of 70% malt germs and 30% dusts. 20 g spores of a type ofmycorrhiza are added to the ton fertilizer, that is, e.g. to the abovementioned ratio of mixture, this mixture being subsequently treated inthe following way:

In order to be capable of converting the mixture of malt germs, fungusmaterial and dusts into a granular form, the pressed material must bemoistened. The dry-matter content typically amounts to between 92 and96%. Moistening through addition of an aqueous fluid is carried out insuch a manner that 12 percent by weight of water is for examplecontained in the mixture consisting of malt germs and dusts.

In a specific embodiment, the aqueous admixture is a commerciallyavailable liquid fertilizer. A small quantity of copper is moreoveradded. The mixture is granulated in a conventional pelletizing orgranulating device. It may then be packaged in quantities that arecustomary in trade and may be offered for sale.

The maximum spreading quantity to the square meter is of approximately1.5 kg. In most cases, a spreading quantity of somewhat short of 1 kg issufficient.

The disclosure of DE 44 24 574 A1 mentioned herein above pertains to thedisclosure content of the present application.

What is claimed is:
 1. Fertilizer grains for plants, the improvementcomprising fertilizer grains containing at least 50 percent by weightmalt germs produced in the process of malting ale cereals and removedfrom the malt grain, and containing at least 10 g mycorrhizal spores, orat least 5 percent by weight mycelium.
 2. The fertilizer grains of claim1 comprising at least 15 percent by weight to the ton of a mycorrhizalfungus.
 3. The fertilizer grains according to claim 1, wherein the meandiameter of the grains is between 2 and 8 mm.
 4. The fertilizer grainsaccording to claim 1 wherein the fertilizer grains include at least 3percent by weight carbohydrates.
 5. The fertilizer grains of claim 4wherein said carbohydrates are selected from the group consisting ofstarch and sugar.
 6. The fertilizer grains according to claim 4, whereinthe carbohydrate contained in the fertilizer grains is maltose.
 7. Thefertilizer grains according to claim 1, wherein the fertilizer grainsinclude a member selected from the group consisting of barley dusts andmalt dusts.
 8. The fertilizer grains of claim 1, wherein the ratio ofmalt germs to dusts is between 2/3 to 3/4 and 1/4.
 9. The fertilizergrains according to claim 1, wherein said grains are granulated orpelletized.
 10. The fertilizer grains according to claim 9, wherein saidgrains contain fertilizer nutrients.
 11. The fertilizer grains accordingto claim 10, wherein said nutrients are selected from the groupconsisting of liquid fertilizer, phosphorous, potassium, magnesium andmicronutrients.
 12. The fertilizer grains according to claim 11, whereinsaid micronutrients are copper.
 13. Ferfilizer grains for plantscomprising: a) at least 50% by weight malt germs; b) at least 10 gramsof mycorrhizal spores; c) at least 5% by weight mycelium; d) at least 3%by weight of carbohydrates; e) barley dust or malt dust, and f)fertilizer nutrients.